Unbound DNS Blacklist

vermaden

Son of Beastie

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Messages: 2,939

Today I will show you how to configure unbound(8) to block spam/malicious/malware domains at DNS level.

unbound


I will use FreeBSD for that purpose but you can use any system that unbound(8) runs on.

logo-freebsd


Earlier I used generated /etc/hosts file but that was limited in several ways. The ZSH shell will autocomplete all these blocked domains to the ssh(1)/scp(1) commands (which takes needless time and shows useless completions). Subdomains are not handled. The malicious.com is blocked but ads.malicious.com is not. You need to duplicate all those domains in the /etc/hosts file.

TL;DR​


Not all people have time for my long boring stories so this is meritum of this article.

Code:
# rm -rf /var/unbound
# mkdir -p /var/unbound/conf.d
# chown -R unbound:unbound /var/unbound
# service local_unbound setup
# service local_unbound enable
# service local_unbound start
# mkdir /root/bin
# cd 
# fetch -o /root/bin/unbound-blacklist-fetch.sh \
> https://raw.githubusercontent.com/vermaden/scripts/master/unbound-blacklist-fetch.sh
# chmod +x /root/bin/unbound-blacklist-fetch.sh
# /root/bin/unbound-blacklist-fetch.sh
# service local_unbound restart
# cat << BSD >> /var/cron/tabs/root
> # FETCH FRESH unbound(8) BLACKLIST
>   0 0 * * * /root/bin/unbound-blacklist-fetch.sh
> BSD


Whole Story​


The unbound(8) caching DNS resolver has been added to FreeBSD base system in 2014 with 10.0-RELEASE version so being on FreeBSD you do not need to install anything. We will start with cleaning the any existing unbound(8) configuration which relies at /var/unbound. Keep in mind that /etc/unbound links to it.

# ls -l -d /etc/unbound /var/unbound
lrwxr-xr-x 1 root wheel 14 2019.09.21 16:23 /etc/unbound -> ../var/unbound
drwxr-xr-x 3 unbound unbound 8 2020.11.17 16:48 /var/unbound

# rm -rf /var/unbound

# mkdir -p /var/unbound/conf.d

# chown -R unbound:unbound /var/unbound


The service local_unbound setup will create all needed configuration.

Just keep in mind that this process will setup all DNS servers that you have in the /etc/resolv.conf file.

You may want to put two of your favorite DNS servers before this process.

Configuration​


# cat << BSD > /etc/resolv.conf
nameserver 9.9.9.9
nameserver 1.1.1.1
BSD


# service local_unbound setup
Performing initial setup.
destination:
Extracting forwarders from /etc/resolv.conf.
/var/unbound/forward.conf created
/var/unbound/lan-zones.conf created
/var/unbound/control.conf created
/var/unbound/unbound.conf created
/etc/resolvconf.conf created
Original /etc/resolv.conf saved as /var/backups/resolv.conf.20201115.235254

# rm /var/backups/resolv.conf.20201115.235254

# find /var/unbound
/var/unbound
/var/unbound/lan-zones.conf
/var/unbound/control.conf
/var/unbound/unbound.conf
/var/unbound/forward.conf

% find /var/unbound -ls
12685 17 drwxr-xr-x 3 unbound unbound 8 Nov 17 16:48 /var/unbound
13072 1 -rw-r--r-- 1 root unbound 98 Nov 17 05:00 /var/unbound/forward.conf
12688 9 -rw-r--r-- 1 root unbound 354 Nov 15 23:56 /var/unbound/unbound.conf
12686 1 drwxr-xr-x 2 unbound unbound 3 Nov 16 00:23 /var/unbound/conf.d
12158 9 -rw-r--r-- 1 root unbound 193 Nov 15 23:56 /var/unbound/control.conf
11732 9 -rw-r--r-- 1 root unbound 189 Nov 15 23:56 /var/unbound/lan-zones.conf

# tail -n 999 /var/unbound/*
==> /var/unbound/conf.d <==
tail: /var/unbound/conf.d: Is a directory

==> /var/unbound/control.conf <==
# This file was generated by local-unbound-setup.
# Modifications will be overwritten.
remote-control:
control-enable: yes
control-interface: /var/run/local_unbound.ctl
control-use-cert: no

==> /var/unbound/forward.conf <==
# Generated by resolvconf

forward-zone:
name: "."
forward-addr: 9.9.9.9
forward-addr: 1.1.1.1

==> /var/unbound/lan-zones.conf <==
# This file was generated by local-unbound-setup.
# Modifications will be overwritten.
server:
# Unblock reverse lookups for LAN addresses
unblock-lan-zones: yes
insecure-lan-zones: yes

==> /var/unbound/unbound.conf <==
# This file was generated by local-unbound-setup.
# Modifications will be overwritten.
server:
username: unbound
directory: /var/unbound
chroot: /var/unbound
pidfile: /var/run/local_unbound.pid
auto-trust-anchor-file: /var/unbound/root.key

include: /var/unbound/lan-zones.conf
include: /var/unbound/control.conf
include: /var/unbound/conf.d/*.conf



We will now enable the local_unbound service and start it. At this point without any DNS blocking configuration.

# service local_unbound enable
local_unbound enabled in /etc/rc.conf

# service local_unbound start
Starting local_unbound.



The /etc/resolv.conf will now have hour favorite DNS servers hashed/disabled and 127.0.0.1 address will be specified. You can also use sockstat(8) to check that unbound(8) is indeed listening on port 53.

# cat /etc/resolv.conf
# nameserver 9.9.9.9
# nameserver 1.1.1.1
nameserver 127.0.0.1
options edns0

% sockstat -l -4
USER COMMAND PID FD PROTO LOCAL ADDRESS FOREIGN ADDRESS
unbound local-unbo 7362 5 udp4 127.0.0.1:53 *:*
unbound local-unbo 7362 6 tcp4 127.0.0.1:53 *:*

Test​


After unbound(8) has been enabled it should now be visible that first DNS request should be longer and the second one and following requests should be very fast.

% time host ftp.freebsd.org
ftp.freebsd.org is an alias for ftp.geo.freebsd.org.
ftp.geo.freebsd.org has address 139.178.72.202
ftp.geo.freebsd.org has address 213.138.116.78
ftp.geo.freebsd.org has address 139.178.72.202
ftp.geo.freebsd.org has IPv6 address 2604:1380:2000:9501::15:0
ftp.geo.freebsd.org has IPv6 address 2001:41c8:112:8300::15:0
ftp.geo.freebsd.org has IPv6 address 2604:1380:2000:9501::15:0
ftp.geo.freebsd.org mail is handled by 0 .
host ftp.freebsd.org 0.00s user 0.01s system 1% cpu 0.501 total

% time host ftp.freebsd.org
ftp.freebsd.org is an alias for ftp.geo.freebsd.org.
ftp.geo.freebsd.org has address 139.178.72.202
ftp.geo.freebsd.org has address 213.138.116.78
ftp.geo.freebsd.org has address 139.178.72.202
ftp.geo.freebsd.org has IPv6 address 2604:1380:2000:9501::15:0
ftp.geo.freebsd.org has IPv6 address 2001:41c8:112:8300::15:0
ftp.geo.freebsd.org has IPv6 address 2604:1380:2000:9501::15:0
ftp.geo.freebsd.org mail is handled by 0 .
host ftp.freebsd.org 0.01s user 0.00s system 88% cpu 0.007 total


Yep. Works.

Blacklist​


I have written a simple and short unbound-blacklist-fetch.sh to automate the process of generating up to date DNS blocked domains config.

It uses one unbound(8) source and several hosts(5) sources, then combines them in unbound(8) compatible format while removing the duplicated entries.

unbound-blacklist-script.256


We will now fetch it, put it under /root/bin directory (or use your favorite one), make it executable and start it.

# mkdir /root/bin

# fetch -o /root/bin/unbound-blacklist-fetch.sh \
>
# chmod +x /root/bin/unbound-blacklist-fetch.sh

# /root/bin/unbound-blacklist-fetch.sh

# ls -l /var/unbound/conf.d/blacklist.conf
-rw-r--r-- 1 root unbound 3003929 2020.11.16 00:23 /var/unbound/conf.d/blacklist.conf

# tail /var/unbound/conf.d/blacklist.conf
local-zone: "zyrtec.1.p2l.info" always_nxdomain
local-zone: "zyrtec.3.p2l.info" always_nxdomain
local-zone: "zyrtec.4.p2l.info" always_nxdomain
local-zone: "zyski-z-innowacji.pl" always_nxdomain
local-zone: "zytpirwai.net" always_nxdomain
local-zone: "zz.cqcounter.com" always_nxdomain
local-zone: "zzhc.vnet.cn" always_nxdomain
local-zone: "zzz.clickbank.net" always_nxdomain
local-zone: "zzz.onion.pet" always_nxdomain
local-zone: "zzzrtrcm2.com" always_nxdomain


The unbound(8) daemon already includes all /var/unbound/conf.d/*.conf files and we use that here.

You can change where the script generates blocked domains config under the # SETTINGS section directly in the script.

% grep -A 5 SETTINGS scripts/unbound-blacklist-fetch.sh
# SETTINGS
FILE=/var/unbound/conf.d/blacklist.conf
TEMP=/tmp/unbound
TYPE=always_nxdomain
ECHO=0



After the /var/unbound/conf.d/blacklist.conf file is generated you can now restart the unbound(8) service.

# service local_unbound restart
Stopping local_unbound.
Waiting for PIDS: 87745.
Starting local_unbound.
Waiting for nameserver to start... good


We will also add that script to crontab(5) so it will fetch fresh information every day.

# cat << BSD >> /var/cron/tabs/root
>
> # FETCH FRESH unbound(8) BLACKLIST
> 0 0 * * * /root/bin/unbound-blacklist-fetch.sh
>
> BSD


# crontab -l | tail -4

# FETCH FRESH unbound(8) BLACKLIST
0 0 * * * /root/bin/unbound-blacklist-fetch.sh


Test Blocked Domains​


From 60000+ blocked domains I have chosen ad.track.us.org as target for verification.

% ping ad.track.us.org
ping: cannot resolve ad.track.us.org: Unknown host

% host ad.track.us.org
Host ad.track.us.org not found: 3(NXDOMAIN)

% dog ad.track.us.org
Status: NXDomain

% dog @1.1.1.1 ad.track.us.org
CNAME ad.track.us.org. 11m30s "track.us.org."
A track.us.org. 6m30s 185.59.208.177




unbound-test.256


As You can see the domain is successfully blocked.

The above blocking configuration does not mean that I will now disable the uBlock Origin plugin from Firefox but its a welcome addition to blocking unwanted information tools workshop.

EOF

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